3d parametric studies using reduced models for self-modulation instability*

An overarching goal of experiments such as AWAKE [1, 2] is the production of TeV-class electron beams utilizing the self-modulation instability (SMI) [3]. In a setup where a laser pulse with ω₀/ω_p > 1000 is used to seed the SMI through a laser-based ionization, reduced simulations based on the ponderomotive guiding center (PGC) solver [4] are promising. In a PGC solver, the temporal scales related the plasma frequency ω_p need to be resolved, but not the laser frequency ω₀ as in full particle-in-cell (PIC) simulation. We present an ionization model used for PGC and its impact on the SMI. Furthermore, we studied the variation of the gas density for the ionization seeding and the stability of the SMI in terms of small parameter fluctuations.

References: 

[1] A. Caldwell et al., Nat. Phys. 5, 363 (2009)

[2] N. Kumar et al., PRL 104, 255003 (2010)

[3] D. Gordon et al., PRE 64, 046404 (2001)

[4] D. Gordon et. al., IEEE Trans. Plasma Sci. 28, 1135 (2000)